Differential activation mechanisms of lipid GPCRs by lysophosphatidic acid and sphingosine 1-phosphate (original) (raw)
Related papers
Nature Communications
Lysophosphatidic acid receptor 1 (LPA1) is one of the six G protein-coupled receptors activated by the bioactive lipid, lysophosphatidic acid (LPA). LPA1 is a drug target for various diseases, including cancer, inflammation, and neuropathic pain. Notably, LPA1 agonists have potential therapeutic value for obesity and urinary incontinence. Here, we report a cryo-electron microscopy structure of the active human LPA1-Gi complex bound to ONO-0740556, an LPA analog with more potent activity against LPA1. Our structure elucidated the details of the agonist binding mode and receptor activation mechanism mediated by rearrangements of transmembrane segment 7 and the central hydrophobic core. A structural comparison of LPA1 and other phylogenetically-related lipid-sensing GPCRs identified the structural determinants for lipid preference of LPA1. Moreover, we characterized the structural polymorphisms at the receptor-G-protein interface, which potentially reflect the G-protein dissociation pr...
Ligand chain length drives activation of lipid G protein-coupled receptors
Scientific Reports, 2017
Sphingosine-1-phosphate (S1P) is a lipid mediator that can activate five cell membrane G protein-coupled receptors (GPCRs) which carry a variety of essential functions and are promising drug targets. S1P is composed of a polar zwitterionic head-group and a hydrophobic alkyl chain. This implies an activation mechanism of its cognate receptor that must be significantly different from what is known for prototypical GPCRs (ie receptor to small hydrophilic ligands). Here we aim to identify the structural features responsible for S1P agonism by combining molecular dynamics simulations and functional assays using S1P analogs of different alkyl chain lengths. We propose that high affinity binding involves polar interactions between the lipid head-group and receptor side chains while activation is due to hydrophobic interactions between the lipid tail and residues in a distinct binding site. We observe that ligand efficacy is directly related to alkyl chain length but also varies with receptor subtypes in correlation with the size of this binding pocket. Integrating experimental and computational data, we propose an activation mechanism for the S1P receptors involving agonist-induced conformational events that are conserved throughout class A GPCRs. By ensuring the conversion of extracellular stimuli into cellular responses, G protein-coupled receptors (GPCRs) modulate signaling pathways in a wide variety of biological processes. The diversity of GPCRs functions is associated with a remarkable variety in their cognate ligands, from both structural and chemical standpoints. Indeed, these receptors bind entities as different as calcium ions, small organic molecules (amines, steroids), nucleotides, peptides, proteins or lipids 1. GPCRs are classified into five main families or classes based on sequence similarity 2 , the class A, also known as rhodopsin family, being the largest and most studied. High-resolution structures of receptors from different families have confirmed that GPCRs share a similar architecture of seven transmem-brane (TM) α-helices forming a bundle and that the TM domains are structurally conserved 3, 4. Class A GPCRs exhibit a distinctive feature that most of their ligands bind to a cavity inside the TM helices. While most of them recognize small polar agonists, GPCRs for lipid mediators are activated by hormone-like signaling molecules derived from lipid species, which possess long hydrophobic moieties 5. This subfamily is mostly composed of the sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) receptors (formerly grouped in the endothelial differentiation gene or EDG family) as well as the cannabinoid receptors. Sphingosine-1-phosphate (S1P) regulates a plethora of biological functions in the central nervous system, immune and cardiovascular systems as well as numerous pathophysiological processes 6. This lysophospholipid is produced intracellularly from sphingolipid catabolism and exerts its functions mainly via activation of five cell membrane specific GPCRs, S1P 1-5 (initially edg-1, 3, 5, 6, and 8) 7. The diversity of S1P signaling and its regulation stems from synthesis and degradation balance, differential expression of S1P receptors in various cell types as well as from their distinct coupling to G proteins subtypes 8. S1P receptors display a variety of essential functions while activated by a unique agonist, conferring them a major therapeutic potential, as underlined by the approval by the US FDA of the S1P 1-mediated immune modulator FTY720 (fingolimod; Gilenya TM , Novartis) for the treatment of relapsing-remitting multiple
Ligand chain length drives activation of lipid G protein-coupled receptors OPEN
Sphingosine-1-phosphate (S1P) is a lipid mediator that can activate five cell membrane G protein-coupled receptors (GPCRs) which carry a variety of essential functions and are promising drug targets. S1P is composed of a polar zwitterionic head-group and a hydrophobic alkyl chain. This implies an activation mechanism of its cognate receptor that must be significantly different from what is known for prototypical GPCRs (ie receptor to small hydrophilic ligands). Here we aim to identify the structural features responsible for S1P agonism by combining molecular dynamics simulations and functional assays using S1P analogs of different alkyl chain lengths. We propose that high affinity binding involves polar interactions between the lipid head-group and receptor side chains while activation is due to hydrophobic interactions between the lipid tail and residues in a distinct binding site. We observe that ligand efficacy is directly related to alkyl chain length but also varies with receptor subtypes in correlation with the size of this binding pocket. Integrating experimental and computational data, we propose an activation mechanism for the S1P receptors involving agonist-induced conformational events that are conserved throughout class A GPCRs. By ensuring the conversion of extracellular stimuli into cellular responses, G protein-coupled receptors (GPCRs) modulate signaling pathways in a wide variety of biological processes. The diversity of GPCRs functions is associated with a remarkable variety in their cognate ligands, from both structural and chemical standpoints. Indeed, these receptors bind entities as different as calcium ions, small organic molecules (amines, steroids), nucleotides, peptides, proteins or lipids 1. GPCRs are classified into five main families or classes based on sequence similarity 2 , the class A, also known as rhodopsin family, being the largest and most studied. High-resolution structures of receptors from different families have confirmed that GPCRs share a similar architecture of seven transmem-brane (TM) α-helices forming a bundle and that the TM domains are structurally conserved 3, 4. Class A GPCRs exhibit a distinctive feature that most of their ligands bind to a cavity inside the TM helices. While most of them recognize small polar agonists, GPCRs for lipid mediators are activated by hormone-like signaling molecules derived from lipid species, which possess long hydrophobic moieties 5. This subfamily is mostly composed of the sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) receptors (formerly grouped in the endothelial differentiation gene or EDG family) as well as the cannabinoid receptors. Sphingosine-1-phosphate (S1P) regulates a plethora of biological functions in the central nervous system, immune and cardiovascular systems as well as numerous pathophysiological processes 6. This lysophospholipid is produced intracellularly from sphingolipid catabolism and exerts its functions mainly via activation of five cell membrane specific GPCRs, S1P 1-5 (initially edg-1, 3, 5, 6, and 8) 7. The diversity of S1P signaling and its regulation stems from synthesis and degradation balance, differential expression of S1P receptors in various cell types as well as from their distinct coupling to G proteins subtypes 8. S1P receptors display a variety of essential functions while activated by a unique agonist, conferring them a major therapeutic potential, as underlined by the approval by the US FDA of the S1P 1-mediated immune modulator FTY720 (fingolimod; Gilenya TM , Novartis) for the treatment of relapsing-remitting multiple
Journal of Lipid Research, 2018
Supplementary key words lipid • phospholipids • endocannabinoid • optical measurement • molecular interaction • binding assay Lysophospholipid (LP) signaling involving cognate G protein-coupled receptors (GPCRs) for lysophosphatidic acid (LPA), sphingosine-1-phosphate (S1P), and other lipids has revealed a vast biology affecting the development and function of most, if not all, organ systems and shown etiological or therapeutic involvement in diseases, including those of the nervous and immune systems, as well as in disease conditions like cancer and fibrosis (1-9). A key step in LP signaling is orthosteric GPCR engagement by binding of a cognate ligand to its receptor, followed by G-protein transduction (10, 11). LP receptor binding is thus a necessary step for both naturally occurring lipids and synthetic ligands that, combined with other members of the GPCR superfamily, account for 40% of currently marketed drugs (12). LP GPCRs are members of the rhodopsin-like family of receptors (class A) from which 40 lipid GPCRs have now been identified (7). Crystal structures for seven lipid GPCRs have been solved including three LP receptors [LPA 1 (13), LPA 6 (14), and S1P 1 (15)] (16). Despite these receptor structural advances, classical pharmacological GPCR-ligand binding assays using radioligands Abstract Lysophosphatidic acid (LPA) activates cognate G protein-coupled receptors (GPCRs) to initiate biological signaling cascades. Lysophospholipid (LP) receptor binding properties remain incompletely assessed because of difficulties with ligand lipophilicity and lipid "stickiness." These inherent attributes produce high levels of nonspecific binding within cell-membrane preparations used to assess GPCRs, as has been shown in classical binding assays using radiolabeled ligands, making accurate measurements of lipid binding kinetics difficult to achieve. Backscattering interferometry (BSI) is an optical technology that measures molecular binding interactions by reporting changes in the refractive index of a solution after binding events. Here, we report the use of BSI to assess LPA 1 for its ability to bind to naturally occurring lipids and a synthetic LPA 1 antagonist (ONO-9780307), under both primary-and competition-binding conditions. Assessment of 12 different lipids demonstrated that the known LP ligand, 1-oleoyl-LPA, as well as an endocannabinoid metabolite, anandamide phosphate, are specific ligands for LPA 1 , whereas other LPs tested were not. Newly determined dissociation constants (K d values) for orthosteric lipid ligands approximated 10 9 M, substantially lower (i.e., with higher affinity) than measured K d values in classical binding or cell-based assays. These results demonstrate that BSI may have particular utility in assessing binding interactions between lipid receptors and their lipid ligands and could provide new screening approaches for lipid receptor identification and drug discovery.
Bioactive Lysophospholipids and Their G Protein-Coupled Receptors
Experimental Cell Research, 1999
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are serum-borne lysophospholipids that signal through their cognate G protein-coupled receptors to evoke a great variety of responses in numerous cell types. In addition to stimulating cell proliferation and survival, LPA and S1P induce profound cytoskeletal changes through Rho-mediated signaling pathways, leading to such diverse responses as cell rounding, neurite retraction, and modulation of tumor cell invasiveness (transcellular migration). A major recent advance is the identification of a subfamily of heptahelical receptors for LPA and S1P.
Anionic Phospholipids Control Mechanisms of GPCR-G Protein Recognition
G protein-coupled receptors (GPCRs) are embedded in phospholipids that strongly influence drug-stimulated signaling. Anionic lipids are particularly important for GPCR signaling complex formation, but a mechanism for this role is not understood. Using NMR spectroscopy, we visualized the impact of anionic lipids on the function-related conformational equilibria of the human A2A adenosine receptor (A2AAR) in bilayers containing defined mixtures of zwitterionic and anionic phospholipids. Anionic lipids primed the receptor to form complexes with G proteins through a conformational selection process. Without anionic lipids, signaling complex formation proceeded through a less favorable induced fit mechanism. In computational models, anionic lipids mimicked interactions between a G protein and positively charged residues in A2AAR at the receptor intracellular surface, stabilizing a pre-activated receptor conformation. Replacing these residues strikingly altered the receptor response to an...
Lysophospholipid (S1P) receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database
IUPHAR/BPS Guide to Pharmacology CITE
Sphingosine 1-phosphate (S1P) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Lysophospholipid receptors [70]) are activated by the endogenous lipid sphingosine 1-phosphate (S1P). Originally cloned as orphan members of the endothelial differentiation gene (edg) family, current gene names have been designated as S1P1R through S1P5R [52]. S1PRs, particularly S1P1, are expressed throughout all mammalian organ systems. Ligand delivery occurs via two known carriers (or "chaperones"): albumin and HDL-bound apolipoprotein M (ApoM), the latter of which elicits biased agonist signaling by S1P1 in multiple cell types [15, 39]. The five S1PRs, two chaperones, and active cellular metabolism have complicated analyses of receptor ligand binding in native systems. Signaling pathways and physiological roles have been characterized through radioligand binding in heterologous expression systems, targeted deletion of the different S1PRs, and most recently, mouse models tha...
2013
Sphingosine 1-phosphate (S1P) is a lysophospholipid mediator which activates G protein-coupled sphingosine 1-phosphate receptors and thus evokes a variety of cell and tissue responses including lymphocyte trafficking, endothelial development, integrity, and maturation. We performed five all-atom 700 ns molecular dynamics simulations of the sphingosine 1phosphate receptor 1 (S1P 1 ) based on recently released crystal structure of that receptor with an antagonist. We found that the initial movements of amino acid residues occurred in the area of highly conserved W269 6.48 in TM6 which is close to the ligand binding location. Those residues located in the central part of the receptor and adjacent to kinks of TM helices comprise of a transmission switch. Side chains movements of those residues were coupled to the movements of water molecules inside the receptor which helped in the gradual opening of intracellular part of the receptor. The most stable parts of the protein were helices TM1 and TM2, while the largest movement was observed for TM7, possibly due to the short intracellular part starting with a helix kink at P 7.50 , which might be the first helix to move at the intracellular side. We show for the first time the detailed view of the concerted action of the transmission switch and Trp (W 6.48 ) rotamer toggle switch leading to redirection of water molecules flow in the central part of the receptor. That event is a prerequisite for subsequent changes in intracellular part of the receptor involving water influx and opening of the receptor structure.
Development of Our Current Understanding of Bioactive Lysophospholipids
Annals of the New York Academy of Sciences, 2006
Lysophosphatidic acid (LPA) serves as the prototypic lysophospholipid mediator that acts through G-protein-coupled receptors to evoke a host of responses in numerous target cells. The hormone-and growth-factor-like activities of LPA, mediated by distinct G proteins, were discovered about 10 years ago. Since then, considerable progress has been made in our understanding of LPA receptor signaling, culminating in the recent identification of a growing family of heptahelical receptors specific for LPA and the structurally related lysolipid, sphingosine-1-phosphate (S1P). In addition to stimulating G i-Rasmediated cell proliferation, LPA and S1P induce rapid G= 12/13-RhoAmediated cytoskeletal changes underlying such diverse responses as neurite retraction, cell rounding, and enhanced tumor cell invasiveness. LPA also triggers inhibition of gap-junctional communication. This overview focuses on how our understanding of LPA as an intercellular lipid mediator has developed during the last decade.